This invention relates to an outboard motor engine and more particularly to an improved balancing arrangement for the internal combustion engine of an outboard motor.
As is well known, outboard motors present certain problems in conjunction with the design of their components due to their compact nature and the fact that the engine normally is positioned with its output shaft rotating about a vertically disposed, rather than a horizontally disposed axis. As is also well known, reciprocating engines have a number of forces and moments which may not be internally balanced within the engine, although balancing masses on the crankshaft are frequently employed.
For many types of engine vibrations, it is desirable to provide a separate balancing shaft or shafts containing one or more balancing weights that are driven from the engine output shaft and which balance the various forces on the engine to reduce vibrations. With outboard motors, it has been the practice to position such balance shafts at the end of the engine with the balance masses at the engine end. This has a number of disadvantages.
In the first instance, by placing the balance mass at the end of the engine although some forces are balanced, undesirable vibrational couples may be generated. In addition, it is undesirable to extend the length of the engine due to its vertical disposition. If the engine is made higher, than the center of gravity of the outboard motor or the propulsion unit is raised and this is not always desirable.
It is, therefore, a principal object to this invention to provide an improved arrangement for balancing an internal combustion engine employed with an outboard motor.
It is a further object to this invention to provide an improved balancing arrangement for an internal combustion engine wherein forces can be balanced and the balancing arrangement can be maintained compact along with the overall engine.
In addition to the problems discussed above, it is also desirable to provide an improved arrangement wherein the balancing shaft for an outboard motor can be adequately supported and yet, provide a compact assembly for the engine. Frequently, the balancing shaft for the engine are journalled by the cylinder block assembly and this gives rise to a complex and sizeable cylinder block.
It is, therefore, a still further object to this invention to provide an improved arrangement for journaling the balancing shaft of an internal combustion engine.